to_latent() dimensional bug fix in Independent based models

[jgallowa07]

Description

This PR primarily enforces that the user pass two dimensional input to the to_latent() function of any of the Independent or independent sub classes.

Closes #169

Tests

Makefile test2d

Checklist:

• [x] The code uses informative and accurate variable and function names
• [x] The functionality is factored out into functions and methods with logical interfaces
• [x] Comments are up to date, document intent, and there are no commented-out code blocks
• [x] Commenting and/or documentation is sufficient for others to be able to understand intent and implementation
• [x] TODOs have been eliminated from the code
• [x] The corresponding issue number (e.g. #278) has been searched for in the code to find relevant notes
• [x] Documentation has been redeployed

[zorian15]

looks like there's still some listing to do -- but other than that I think this is good to merge